With the enhancement in computer performance and broadband networks, services for delivering contents such as videos and images to users become widely used. With this, variations of providing contents and infrastructures used to deliver contents have become diverse. In the following explanation, variations for delivering a content (which is a combination of variation for providing a content and an infrastructure) is described as the delivery variation.
As some examples of the content delivery variations, the broadcast, the multicast, and the on-demand (unicast) can be referred to. In the broadcast, a plurality of contents are delivered to all users. The user selects and watches a desired content among the plurality of delivered contents. In the multicast, the user selects a desired channel. In the channel, a predetermined content is delivered to the user desiring the channel at a predetermined period (or a schedule). In the on-demand, the user selects a content to watch. Then, the selected content is delivered to the user.
On the other hand, as the infrastructure, for example, a ground wave, a satellite broadcasting, the Internet, a dedicated line can be referred to.
Here, a case is considered in which a company who provides content delivery services is able to deliver a content through a plurality of delivery variations. In such a case, a delivery variation desirable for the company is not always one which is desirable for users. For example, it is assumed that the company has a delivery variation in which an image content is delivered through the Internet by multicast. Such a delivery content is highly desirable for the company side in view of the low delivery cost. However, for a user, such a delivery variation may be inconvenient caused by various reasons such that the content is not available at a desired time or the image quality is deteriorated by packet loss or jitter and so on. If the number of users decreases by such inconveniences, it becomes critical loss for the company side.
Then, it is desired that an optimum delivery variation is selected from a plurality of delivery variations.
A related technique is described in Japanese Patent Application Publication JP-2001-283015A. In this literature, a content management server, a plurality of delivery servers which download content data in response to a request from a user terminal, and a distribution route transmission server are included. The content management server refers to a condition for responding to a download request from a user terminal and an activity condition of the distribution server, compares with a current content supply capability, identifies a delivery server which has a capability to supply content data to the user terminal under a set condition, and sends distribution route information which includes charging information required for the delivery from the distribution server to the distribution route transmission server and the user terminal. The user terminal selects a route desirable for itself from them and sends it to the distribution route transmission server.
Further, the followings are some of related techniques which have been available to the inventor of the present invention: Japanese Patent Application Publication JP-2002-92502A; JP-2006-39952A; and JP-2006-203720A.